I understand where you're coming from... which is why I watch for sales (both here and elsewhere), and "shop" on eBay for many of my acquisitions.
However, if I understand correctly -- most of GHQ's costs come from the tooling and the machinery used to make these models. The difference in cost for the metal used from a "jeep" to an MBT is rather small -- but the tooling, dies, casting machinery, packaging, handling, administrative costs, plus enough of a profit to stay in business would be pretty much the same for each pack. Hence, the uniform pricing.
They could probably charge us a few cents less for a pack of "jeeps", and a few cents more for a pack of MBT's -- but it's probably easier for all concerned to "average" the costs across the product line and simplify the pricing process.
I've often wondered why many retail businesses don't factor in the price of sales tax, "average" or "round off" as necessary, and eliminate the penny from the pricing equation. Indeed, I've seen at sporting arenas (for example), where a beverage is listed as $3.00 -- and then in small print below you see something like beverage = $2.68 + 32 cents tax = $3.00.
I know it's a marketing ploy to mark something at $99.95 instead of $100.00 -- that many folks are somewhat fooled by the appearance of a "good deal". I also remember my late father telling me about a local farmer sold eggs at a roadside stand... 30 cents a dozen or three dozen for $1.00 -- and how many people thought they were getting a good deal and would buy three dozen!
Going back to your post... I would guess that is why a pack of "jeeps" costs as much as a pack of MBT's. Hmmmm... maybe we should look at it the other way -- we're getting a pack of MBT's for the same price as a pack of "jeeps"!!

Regards,
Tom Stockton